1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method in which a wafer formed with devices in a plurality of areas sectioned by streets formed in a lattice like pattern on the front surface thereof is divided into the individual devices along the streets and a die bonding adhesive film is attached to the rear surface of each of the devices.
2. Description of the Related Art
For example, in a semiconductor device manufacturing step, devices such as ICs, LSIs or the like are formed in a plurality of areas sectioned by predetermined dividing lines (streets) formed in a lattice-like pattern on the front surface of a generally disk-shaped semiconductor wafer. The areas formed with the devices are divided along the streets. Thus, the individual semiconductor devices are manufactured. A dicing device is generally used as a dividing device for dividing the semiconductor wafer. The dicing device cuts the semiconductor wafer along the streets by means of a cutting blade with a thickness of approximately 20 μm. The semiconductor devices divided as described above are widely used in electric devices such as mobile phones, personal computers, etc.
The individually divided semiconductor devices are each attached on the rear surface with a die bonding adhesive film called a die attach film. The die bonding adhesive film is formed of a polyimide-based resin, an epoxy-base resin, an acryl-based resin or the like to have a thickness of 20 to 40 μm. Further, the individually divided semiconductors are bonded, by heating, to a die bonding frame supporting the semiconductor devices via the adhesive film. One of methods of attaching a die bonding adhesive film to the rear surface of a semiconductor device is as below. An adhesive film is applied to the rear surface of a semiconductor wafer. The semiconductor wafer is applied to a dicing tape via the adhesive film. Thereafter, the semiconductor wafer is cut together with the adhesive film by a cutting blade along streets formed on the front surface of the semiconductor wafer. Thus, the semiconductor devices attached with the adhesive films on the rear surface are formed. (See e.g. Japanese Patent Laid-Open No. 2000-182995.)
According to the method disclosed in Japanese Patent Laid-Open No. 2000-182995, however, when the semiconductor wafer is cut together with the adhesive film by means of the cutting blade and divided into the individual semiconductor devices, the rear surface of the semiconductor device may cause a chip or the adhesive film may cause beard-like burrs. This poses a problem of disconnection occurring during wire bonding.
In recent years, electric devices such as mobile phones, personal computers, etc. have required weight reduction and downsizing, which has required thinner semiconductor devices. A dividing technique called the so-called dicing before grinding process is put to practical use as a technique for dividing semiconductor devices thinner. The dicing before grinding process is a technique as below. Cut grooves are formed along streets at a given depth (the depth corresponding to the finish thickness of the semiconductor device) from the front surface of the semiconductor wafer. Thereafter, the semiconductor wafer formed with the cut grooves on the front surface is ground from its rear surface to expose the cut grooves to the rear surface. Thus, the semiconductor wafer is divided into individual semiconductor devices. The semiconductor devices can each be processed to have a thickness of 50 μm or less.
The semiconductor wafer is divided into the individual semiconductor devices by the dicing before grinding process. In such a case, however, the cut grooves are formed along the streets to have the given depth from the front surface of the semiconductor wafer. Thereafter, the semiconductor wafer is ground from the rear surface to expose the cut grooves to the rear surface. Therefore, a die bonding adhesive film cannot previously be attached to the rear surface of the semiconductor wafer. Thus, when the semiconductor device is bonded, by the dicing before grinding process, to the die bonding frame supporting the semiconductor device, the die bonding has to be performed while pouring bond between the semiconductor device and the die bonding frame. This poses a problem in that bonding work cannot be performed smoothly.
To solve such a problem, a semiconductor device manufacturing method as described below is proposed. In this method, a die bonding adhesive film is attached to the rear surface of a wafer which is divided into individual semiconductor devices by the dicing before grinding process. The semiconductor devices are attached to a dicing tape via the adhesive film. Thereafter, a laser beam is directed to a portion of the adhesive film exposed to the gap between the semiconductor devices, from the front surface side of the semiconductor device via the gap. Thus, the portion of the adhesive film exposed to the gap between is removed. (See e.g. Japanese Patent Laid-Open No. 2002-118081.)
In this way, a laser beam is directed to the die bonding adhesive film attached to the rear surface of the wafer divided into the individual semiconductor devices, through the gap between the semiconductor devices for fusion-cutting the adhesive film. In this case, debris fly off and attach to the front surface of the device, which poses a problem of degrading the quality of the semiconductor device.
A protection tape is applied to the front surface of a wafer formed with cut grooves, and the wafer is ground from its rear surface and divided into individual semiconductor devices. In this case, the individually divided semiconductor devices shift so that the cut grooves meander. This poses a problem in that it is difficult to direct a laser beam through the gap between the semiconductor devices after the die bonding adhesive film has been attached to the rear surface of the individually divided semiconductor devices.